System and method of electroslag remelting of metals and alloys

ABSTRACT

In an electroslag remelting process, electrode means preferably comprising at least two electrodes are immersed in a molten slag bath in a mold and AC power is applied between the electrodes. An electric connection is provided between the bottom plate of the mold and a center tap of the power supply to insure equal melting rates of the electrodes of the electrode means. Means are provided to improve the electrical connection between the sidewalls and the bottom plate of the mold and between the bottom plate and the ingot which is formed in the mold. A plurality of water channels directly beneath the bottom plate provides improved cooling thereof. Means are provided for moving the mold horizontally in two dimensions with respect to the electrodes. Means are provided to prevent the electrodes from flying apart when current first starts to flow through the electrodes. Ingots of different sizes can be formed using electrodes which are uniform in size.

United States Patent 1191 Paton et a1.

[ 1 SYSTEM AND METHOD OF ELECTROSLAG REMELTING OF METALS AND ALLOYS [76] Inventors: Boris Evgenievich Paton, ulitsa Kotsyubinskogo, 9, apt. 21; Boris Izrailevich Medovar, Boulevard Lesi Ukrainki, 2, apt. 8; Jury Vadimovich Latash, Vozduhoflotsky Prospekt, 81, apt. 14; Vladimir Konstantinovich Lebedev, ulitsa Engelsa, 25, apt. 12; Vitaly Michailovich Baglay, ulitsa 145 Oct. 16, 1973 Semashko, 10, apt. 54/3; Oleg Petrovich Bondarenko, ulitsa Kreshchatik, l5, apt. 34; Michail Nikolaevich Sidorenko, ulitsa Vladimirskaya, 98, apt. 54; Alexey Georgievich Bogachenko, ulitsa Milyutenko, 15/2, apt. 141, all of Kiev, U.S.S.R.

[22] Filed: Feb. 19, 1970 [211 App]. No.: 12,601

[52] U.S. Cl. 164/252, 164/52 [51] Int. Cl B2211 27/02 [58] Field Of Search 164/52, 252, 50; 75/10 C; 277/236; l3/DIG. 1

[56] References Cited UNITED STATES PATENTS 2,279,990 4/1942 Hopkins 164/252 2,385,206 9/1945 Hopkins 164/52 2,761,002 8/1956 Laird et al. 165/252 x 3,220,067 11/1965 Hopkins 164/52 1,609,283 12/1926 Bailey 277/236 2,984,876 5/1961 Garmy 164/252 3,049,769 8/1962 Schultz 164/348 x 2,154,234 4/1939 Eppensteiner 164/348 X Primary Examiner-R. Spencer Annear Attorney-Lane, Aitken, Dunner & Ziems [57] ABSTRACT In an electroslag remelting process, electrode means preferably comprising at least two electrodes are immersed in a molten slag bath in a mold and AC power is applied between the electrodes. An electric connection is provided between the bottom plate of the mold and a center tap of the power supply to insure equal melting rates ofthe electrodes of the electrode means. Means are provided to improve the electrical connection between the sidewalls and the bottom plate of the mold and between the bottom plate and the ingot which is formed in the mold. A plurality of water channels directly beneath, the bottom plate provides improved cooling thereof. Means are provided for moving the mold horizontally in two dimensions with respect to the electrodes. Means are provided to prevent the electrodes from flying apart when current first starts to flow through the electrodes. ingots of different sizes can be formed using electrodes which are uniform in size.

49 Claims, 14 Drawing Figures PATENTEDUBI 16 Ian 3.765411 INVENTORS BORIS EVGENIEVICH PATON BORIS IZRAILEVICH MEDOVAR JURY VADIMOVICH LATASH VLADIMIR KONSTANTINOVICH LEBEDEV VITALY MICHAILOVICH BAGLAY OLEG PETROVICH BONDARENKO MICHAIL NIKOLAEVICH SIDORENKO 8 ALEXEY GEORGIEVICH BOGACHENKO l A oamsvs PATENTEU [JCT 16 I973 SHEET 3 0F 7 FIG.4.

IOI

PMEMTEnnm 16 ms 3.765.471 SHEET 8 BF 7 FIG.8.

SYSTEM AND METHOD OF ELECTROSLAG REMELTING OF METALS AND ALLOYS BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates to the electroslag remelting of metals and alloys in a cooled mold from two consumable electrodes and to specific improvements in electroslag systems and methods which can be used generally with such a plurality of electrodes or with single electrodes or two groups of such electrodes.

In particular, disclosed in US. Pat. No. 670,299 of Belgium is a similar installation, capable of producing ingots of a fairly high quality.

The known installation is provided with a mold placed on a bottom plate, in which a slag bath is prepared by any conventional method. Two consumable electrodes or two groups of consumable electrodes are immersed into this bath, said electrodes being connected in series to the secondary winding of a singlephase power transformer, employed as a power supply source for the installation, the electrodes being moved together during the operation by a feeding mechanism while being melted in the slag bath.

The specified remelting conditions are maintained by controlling the magnitude of current and voltage by transferring the electrodes and switching over the voltage stages of the transformer, respectively.

The aforedescribed system of electroslag remelting, using two consumable electrodes or two groups of such electrodes, as opposed to the system in which power is applied between the base plate of the mold and'one or more electrodes, is referred to as the bifilar system. The system of electroslag remelting in which the power is applied between the base plate and a single electrode or a group of electrodes is referred to as the monophase system. The bifilar system of electroslag remelting has significant advantages over the monophase system of electroslag remelting. Because the power is applied between two closely spaced electrodes, separation of the conductors supplying power to the system is minimized and accordingly the inductance of the system is significantly reduced. As a result, the bifilar system has'a lower power factor than the monophase system and only 60 to 80 percent as much power is required in the bifilar system to produce a given size ingot as is required in the monophase system. In addition, a lower power transformer can be used to produce an ingot of a given size than can be used in the monophase system.

In some cases, however, in the bifilar process of electroslag remelting, as carried out in the existing installations, the equality of linear speeds of melting of each electrode or electrodes of each two groups may be disturbed. These disturbances may be caused, for example, by a local difference in the cross-sections of the electrodes, by the presence of porosity therein, and a misalignment of electrodes with respect to the mold.

In case of a long-time disturbance of the equality in the linear speeds of melting the electrodes, a gradually increasing misalignment of the electrodes is observed such that one of the electrodes may happen to be immersed into the liquid metal bath, i.e., an emergency mode of operation of the installation is possible.

To eliminate said disadvantages, it was required to provide an installation for the electroslag remelting of consumable electrodes, in which the electrodes would be connected in the electric circuit of the power transfonner in such a manner that their melting during the operation be uniform.

The present invention features an installation for the electroslag remelting of two consumable electrodes or two groups of consumable electrodes, which are connected in series into the circuit of the power supply source, and are immersed into a slag bath prepared in a mold being placed on a cooled bottom plate. These electrodes are moved together by a common feeding mechanism while being melted in the slag bath. In conformity with the invention, a conductor of equalizing current is made to connect the supply source to the slag bath being prepared in the mold.

It is advisable to connect one end of the conductor of equalizing current to the point of half-voltage of the secondary winding of the transformer of said power supply source, while the other end thereof is connected to the bottom plate or the mold.

If for some reasons it is impossible to tap off the point of half-voltage of. the secondary winding of the transformer, one end of the conductor of equalizing current may be connected to the point of half-voltage of the winding of a choke, which is connected in parallel with the secondary winding of the transformer. The other end of the conductor of equalizing current is also connected either to the bottom plate or the mold.

When remelting in the installation, designed according to the present invention, entirely identical electrodes, disposed strictly symmetrically relative to the mold, the current of the same magnitude is flowing through each 'of the electrodes; the same amount of power is evolved at each electrode immersed in the liquid slag; the depth of immersion of the electrodes into the slag bath is the same, and the conductor of equalizing current is deenergized.

In case of misalignment of the electrodes due to a short-time influence of any of the above-said factors, the intensity of current, flowing in the electrode immersed deeper into the slag bath, becomes higher than that of the current flowing through the electrode immersed to a smaller extent, the difference being equal to the magnitude of equalizing current, which will then flow through the conductor of equalizing current. On account of such a variation in the currents flowing through the electrodes, the power evolved at the electrode immersed deeper into the slag bath will be greater than that at the electrode immersed to a smaller extent. This will result in eliminating the misalignment and reducing the equalizing current to zero.

In the case of pennanently acting factors, causing the misalignment of the electrodes, such a ratio of currents equality in the linear speeds of melting of the electrodes, and also to completely eliminate the possibility of emergency operation.

When the equalizing wire is not used, then as pointed out above, the cross-sectional area of the two' electrodes must be equal or nearly equal. In addition, the

' two electrodes must be symmetrically disposed in the molten slag bathand good electrical contact must be maintained between'the mold sidewalls and the base plate of the mold and between the base plate and the ingot. If the electrodes are not symmetrically disposed in the mold, then current, in addition to flowing directly between the electrodes through the slag-bath and through the molten metal pool, may flow into the sidewall of the mold. If this current should flow back out of the sidewall into the ingot being formed it will cause a defect in the ingot. Moreover, such a defect is easily overlooked because it exhibits only small evidence of its presence on the surface of the ingot, even though the, defect is quite extensive within the ingot. If good contact is maintained between the mold sidewalls and the base plate and between the base plate and the ingot, then current flowing into the sidewalls of the mold will flow from the sidewalls into the base plate and then from the base plate into the ingot, rather than back out through the sidewalls into the ingot and cause a defect. Thus, in order to minimize the likelihood of occurrence of such defects, the electrodes should be maintained symmetrically positioned in the mold and good electrical contact should be maintained between the sidewalls of the mold and the base plate of the mold and between the base plate and the ingot.

Because the electrodes may not be perfectly aligned, the electrodes may not maintain their symmetry with respect to the mold as they are melted and fed downwardly into the mold. In accordance with one embodiment of the present invention, to maintain the symmetrical positioning of the electrodes in the mold, means are provided to move the mold horizontally in two dimensions. Movement in one dimension is provided by the dolly on which the mold is supported during remelting and movement in the second horizontal dimension is provided by means of a support which in turn is supported on the dolly. As the electrodes are remelted, the

dolly and the support are selectively operated to move the mold to maintain the electrodes symmetrically positioned in the mold.

To maintain good electrical contact between the mold sidewalls and the base plate, the sidewalls are made out of copper and are provided with a flange extending around the bottom of the mold. Clamps are provided to firmly press the flange against the base plate. In addition, copper foil folded into several layers is between the base plate and the flange.

To maintain excellent electrical contact between the base plate and the ingot, the base plate is provided with a recess in which a piece of metal of the same composition as the ingot is fitted. This piece of metal is referred to as the seed charge. The seed charge extends up above the top surface of the base plate and sideways pressure is exerted against the seed charge in the recess to press it firmly against the bottom plate. When remelting begins in the molten slag bath, the top of the seed charge extending into the bottom of the mold will melt and weld to the ingot. Thus, excellent electrical contact will be obtained between the base plate and the ingot.

Improved'cooling of the base plate is provided by defining a plurality of water channels defined in the top surface of a plate located directly beneath the base plate and by causing water to flow through these channels at a high rate. This improved cooling enables a thicker base plate to be used thus making room for the recess in the base plate in which the seed charge is located. In addition, the thicker base plate reduces sagging of the base plate under the weight of the ingot,

which sagging interferes with the good electrical contact required between the mold and the base plate. In addition, the reduction of the sagging of the base plate gives better form to the bottom of the ingot which is produced.

In the bifilar system of electroslag remelting, the electrodes may take many different shapes. In accordance with the preferred embodiment of the present invention, the electrodes are either in the form of slabs or are square in cross section and the ingot which is formed in the process is rectangular in cross section. In accordance with one aspect of the present invention, when slab electrodes are used to form ingots of different sizes, slabs of the same thickness are used for each difierent ingot size and only the width of the slab electrodesis changed. This enables the electrodes for forming the different sizes of ingots to be obtained more cheaply. When ingots of different sizes are to be formed using electrodes with square cross sections, electrodes of the same size are used but are spaced different distances apart in the mold. Again this feature enables the electrodes to be obtained more cheaply for forming ingots of different sizes.

BRIEF DESCRIPTION OF THE DRAWINGS Possible embodiments of the invention willnow be described by way of example with reference to the accompanying drawings, wherein:

FIG. 1 represents an installation for the electroslag remelting according to the invention, wherein the bottom plate is connected by means of a conductor of equalizing current to the point of half-voltage of the secondary winding of a single-phase power transformer;

FIG. 2 represents the same installation, wherein the bottom plate is connected by means of a conductor of equalizing current to the point of half-voltage of the winding of an equalizing choke connected in parallel to the secondary winding of the single-phase transformer;

FIG. 3 represents an equivalent electrical circuit diagram of the installation of FIG. 1, according to the invention;

FIG. 4 is a side view in elevation of another embodiment of the present invention;

FIG. 5 is a front view in elevation of the embodiment of FIG. 4;

FIG. 6 is a sectional view taken along the lines 6-6 of FIG. 5 illustrating details of the bottom plate in the embodiment of FIGS. 4 and 5;

FIG. 7 is a sectional view taken along the lines 77 of FIG. 5 illustrating details of the bottom plate and of the support for the bottom plate in the embodiment of FIGS. 4 and 5;

FIG. 8 is a partial sectional view of the embodiment of FIGS. 4 and 5 illustrating the electrodes immersed in themolten slag bath;

FIG. 9 is a schematic illustration of the embodiment of FIGS. 4 and 5 showing how electrical connections including an equalizing current conductor are made to this embodiment;

FIG. 10 is a schematic illustration showing the alternative manner of making an electrical connection to the embodiment of FIGS. 4 and 5;

FIGS. 11 and 12 are sectional views taken horizontally through the electrodes illustrating how slab and square cross section electrodes are positioned in the mold and also illustrating structure to counteract the tendency of electrodes to fly apart when current first starts to flow through the electrodes; and,

FIGS. 13 and 14 schematically illustrate the arrangement of slab and rectangular cross section electrodes in the mold showing'how different ingots of different sizes are formed using these electrodes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION In the embodiments of the invention, represented in FIGS. 1 and 2, the installation is provided with a supporting column I mounting a mechanism 2 for feeding electrodes 3 and 4, to be introduced together into a slag bath 5, as prepared in a mold 6 intended for shaping an ingot 7, built up from electrodes 3 and 4.

The mold 6 comprises a bottom plate 8, on which are placed the sidewalls 8a of the mold, and connected with a lifting mechanism 9 mounted on the column 1.

The electrodes 3 and 4 are connected in series to a single-phase power transformer 10, being the supply source of the installation, said electrodes being moved simultaneously by the mechanism 2 while melting down in the slag bath 5. As the electrodes melt, the liquid metal forms into drops on the electrodes and the liquid metal drops pass through the molten slag into a molten pool of metal formed between the solidified ingot 7 and the molten slag 5. The slag refines the liquid metal and as a result an ingot of high quality is formed in the mold.

One end of a conductor 11 of equalizing current is connected to the bottom plate 8, while the other end thereof is connected to the point of half-voltage of the secondary winding 12 of the single-phase power transformer 10, as shown in FIG. 1.

In case the conductor 11 of equalizing current cannot, for some reason, be connected to the point 0 of half-voltage of the secondary winding of the singlephase power transformer 10, an equalizing choke 13 can be employed, to be connected in parallel with said secondary winding 12 of the transformer 10.

The conductor 11 of equalizing current is then connected to the point 0 of halfwoltage of a winding 14 of the equalizing choke 13, as it is shown in FIG. 2, and to the bottom plate 8. I

The equalizing choke operates as an autotransformer having the transformation ratio equal to two.

The principle of operation of the installation of the invention is described in conformity with the installation, as illustratedin FIG. 1, whose equivalent electrical circuit diagram is represented in FIG. 3.

On the diagram of FIG. 3, numerals 15 and 16 correspondingly designate the resistances of slag in the circuit, constituted by the electrode 3-slag-metal bath and mold-slagelectrode 4, while the resistance of slag between the electrodes is indicated by numeral 17.

As it is obvious from the diagram, current flows in the slag bath through two circuits via the resistance 17 and the resistances and 16.

When the electrodes are immersed into the liquid slag to an equal depth, the resistances l5 and 16 are of equal value, the equalizing current in the conductor 11 is absent, since the drop of voltage across the resistance 15 and resistance 16 (the resistances of the short cir cuit to each electrode and the resistances of the electrodes being not shown in the equivalent diagram) are equal to each other and to the half-volage of the secondary winding 12 of the transformer, i.e., the points A and O are points of the same potential.

In this case the installation operates according to a purely bifilar circuit diagram, the same current flowing through each electrode.

In case of short-time action of one or a plurality of factors causing the inequality in the linear speeds of melting of the electrodes, one of the electrodes is immersed into the slag to a greater depth than the second one. For example, the electrode 4 will be immersed to a greater depth. Then the value of resistance 16 will be decreased as compared with the resistance 15, because the distance 1 between the end of the electrode 4 and metal bath 18 will be smaller than the distance I between this bath and the end of the electrode 3. Owing to the fact that the resistance 16 is smaller than the resistance 15, a portion of the current of the electrode 4 will flow, bypassing the electrode 3, along the conductor 1 1 to the point of half-voltage of the secondary winding 12 of the transformer 10. Thus, a greater amount of power will be evolved in the slag at the electrode 4 than that at the electrode 3, which will result in an increase in the speed of melting of the electrode 4 and in a decrease in the speed of melting of the electrode 3, i.e., in the elimination of the misalignment.

When constant factors are acting, causing the misalignment, an equalizing currentwill constantly flow through the conductor of equalizing current, said current being sufficient for equalizing the linear speeds of melting of the electrodes, the values of the depths of electrodes is equal to 20 percent. The magnitude of the equalizing current amounted to 18 percent of the intensity of current flowing through the electrode of a smaller cross-sectional area.

Yet the remelting of electrodes, having such a difference between the cross-sectional areas, proves to be impracticable in the conventional installation, provided with the mechanism for simultaneous feeding of the electrodes, because in the course of the melt the depth of immersion of the electrode with a greater crosssectional area gradually increases, and the electrode end is thus immersed into the metal bath.

In the embodiment shown in FIGS. 4-8, a supporting column 31 has mounted thereon a mechanism 33 for feeding two electrodes 34 and 35 into a slag bath prepared in a mold comprising sidewalls 37 supported on a base plate 39. As in the embodiments of FIGS. 1-3, the electrodes 34 and 35 are fed simultaneously by the I feeding mechanism 33, which moves on the support column 31. As shown in FIGS. 9 and 10, power is applied from a transformer 40 between the two electrodes 34 and 35 causing the current to flow between the electrodes through the molten slag bath 36, thus applying heat to the molten slag bath and melting the electrodes.

Accordingly, a molten pool of metal 41 collects in the bottom of the mold, which molten pool of metal solidifies into an ingot starting from the bottom of the mold as the electrodes are melted. As the ingot solidifies, a molten pool of metal will be maintained between the solidified ingot and the molten slag by the continuous melting of the electrodes. As the electrodes melt, the feeding mechanism 33 feeds the electrodes downwardly into the mold maintaining the ends thereof immersedv in the molten slag.

As best shown in F168. 4, 5, 7 and 8, the base plate 39 is positioned on a support 43, which in turn is supported on a dolly 45. The dolly can be driven by an electric motor (not shown) and a transmission including gear 46 along tracks 47 to move the mold horizontally in one direction. Power for energizing the electric motor to drive the dolly is picked up between the tracks 47 by means of a trolley connection 49. The support 43 provides a means for movingthe mold also in a horizontal direction, but perpendicularly to the direction of movement provided by the dolly 45. The support 43 comprises a top plate 51, which is movable along guide ways 53 with respect to the base of the support'43. The driving of the top plate 51 is accomplished by means of a nut 55, which is fixed to the middle of top plate 51 and which is threaded on a screw 57. The screw 57 can be rotated from the electric motor mounted in the dolly 45 by means of a transmission 59' which extends from the support 43 down into the dolly 45. The motor in the dolly 45 can be made to selectively drive either the dolly 45 along the tracks 47 on the screw 57'by means of conventional clutches, which are not shown. Thus, the mold may be selectively moved horizontally in two dimensions or directions by either driving the dolly alongthe tracks 47 or driving the top plate 51 of the support 43.

Because the electrodes 34 and 35 may not be perfectly aligned, as they are melted and fed down into the bath of molten slag, they may not remain symmetrically positioned in the mold. if the position of the electrodesshould become unsymmetrical, current may flow from one of the electrodes into the sidewalls 37 and then back out of the sidewalls into the solidifying ingot and thus cause a defect in the ingot. As pointed out above, such a defect is dangerous because the evidence of the defect on the surface of the ingot where the current enters the ingot from the sidewall is very small, whereas the defect enlarges going into the ingot. To prevent such defects from forming, the support 43 and the dolly I 45 are controlled to move the mold horizontally in two dimensions to maintain the electrodes symmetrically positioned in the mold as the electrodes are melted and fed down into the molten slag bath. To further insure against the formation of such defects, the sidewalls 37 of the mold are made of copper and are provided with an outwardly extending flange 61, which rests on the bottom plate 39. Clamps 63 are mounted on the bottom plate 39 around the mold to firmly press theflange 61 down against the bottom plate to thereby improve the electrical connection between the sidewalls 37 and the bottom plate 39. To further improve the electrical connection between the sidewalls 37 and the bottom plate 39, copper foil 65 folded into several layers is pressed between the flange 61 and the bottom plate 39 extending all around the mold. To provide a perfect electrical connection between the ingot being formed in the mold and the bottom plate 39, a rectangular recess 67 is defined extending down into the bottom plate 39 from the top surface thereof forming the bottom of the mold. In this recess is fitted a rectangular piece of metal 69 of the same composition as the ingot which is to be formed in the mold by the electroslag remelting process. The piece of metal 69 is referred to as a seed charge. A cylindrical passage 71 is defined in the bottom plate 39 extending horizontally from the rectangular recess 67 to the sidewalls of the bottom plate 39. In this cylindrical passage 71 is slidably mounted a pin 73, which engage the seed charge 69. The outer end of the pin 73 is slidably held in a U-shaped bracket 75, which is mounted on the sidewall of the bottom plate 39. The pin is provided with a collar 77 on the portion thereof that extends between the bracket 75 and the sidewall of the bottom plate 39. A coil spring 79 surrounds the portion of the pin 73 between the collar 77 and the U- shaped bracket 75 and applies a force against the collar 77 urging the pin 73 against'the seed charge 69. As a result, the seed charge 69 is pressed against the side of the recess 67 and in this manner an excellent electrical contact is obtained between the seed charge 69 and the bottom plate 39. When the molten slag bath is first prepared in the mold, the heat of the molten slag will cause the top of the seed charge 69 extending up into the mold to melt'as is illustrated in FIG. 7 and the molten pool 41, which is initially formed in the bottom of the mold, will come in contact with the melted upper portion of the seed charge 69. As a result, when the ingot starts to solidify the seed charge 69 will be welded to the solidified ingot and an excellent electrical contact will be obtained between the seed charge and the ingot and thus between the ingot and the bottom plate 39.

The good electrical contact provided between the sidewalls 37 and the bottom plate 39 and the excellent electrical contact between the ingot and the bottom plate 39 also. serves to prevent defects of the type caused by current flowing from the sidewalls back into the ingot as it is being formed. If current should flow from one of the electrodes into the sidewalls 37, the

the ingot. This latter current path will be of a higher resistance because of the thin skin of solidified slag which forms on the inner surface of the sidewalls 37. In this manner, defects caused by current flowing from the sidewalls into the ingot as it is being formed are prevented Between the support 43 and the bottom plate 39,

there is provided means to cool the bottom plate 39.

This cooling means takes the form of a plate 81, in the top of which are formed channels 83 extending from one end of the plate 81 to the other throughout the length of the bottom plate 39. Water is caused to flow through these channels at a high rate of speed thus providing excellent cooling of the bottom plate 39. As shown in FIG. 6, water is introduced into the channels through an inlet 85 and removed at the other end of the channels through an outlet 87. Because of the excellent cooling provided by the water flowing at a high speed through the channels 83, the plate 39 can be made thicker than with the cooling apparatus of the prior art and thus can be made thick enough to form the recess 67, in which the seed charge 69 is fitted. In addition, the thicker plate 39 permitted by the improved cooling member 81 reduces the sagging of the bottom plate 39 under the weight of the ingot formed in the mold, which sagging would otherwise interfere with the electrical connection that is obtained between the sidewalls 37 and the bottom plate 39. Thus, the improved cooling provided by the member 81 indirectly improves the electrical connection between the sidewalls 37 and the bottom plate 39. In addition, the reduced sagging of the bottom plate 39 provides a better form to the'bottom of the ingot, which is formed in the mold.

When the ingot has been formed in the mold, the sidewalls 37 may be attached to a lifting mechanism '90, which is movable up and down the support column 31, to lift the sidewalls 37 off of the ingot. The dolly 45 may then be used to carry the ingot away from the column 31.

The embodiment'of the invention shown in FIGS. 4-8 can also employ an equalizing current connection as is used in the embodiment of FIG. 1. Such a connection 91 is schematically shown in FIG. 9 running from the center tap of the secondary of the transformer 40 to the bottom plate 39. This equalizing current connector as in the embodiment of FIG. 1 will maintain the melting rates of the electrodes equal even though significant differences in the cross-sectional area of the electrodes or in the porosity of the electrodes should occur. As in the embodiment of FIG. 2, instead of connecting the equalizing current conductor between the center tap of the secondary winding of the transformer 40 and the bottom plate 39, the transformer 49 may be connected across a choke coil 93, as is shown in FIG. 10, and an equalizing current conductor 95 connected between a center tap on this choke coil 93 and the bottom plate 39.

As shown in FIGS. 9 and 10, voltmeters 99 are connected between each of the electrodes and the bottom plate 39 to measure the voltage between these electrodes and the bottom plate. These voltmeters are particularly important when the equalizing current connector is not used and is disconnected from the bottom plate. The voltmeters 99 provide an indication of how close the electrode to which they are connected is to the molten pool of metal beneath the bath of molten slag. Should one of the electrodes 34 or 35 start melting faster than the other so that the other electrode approaches the molten pool 41 of metal, the voltage indicated by voltmeter 99 connected to this electrode will drop to a low value. When the voltage indicated by one of the voltrneters 99 drops below a predetermined minimum selected to provide an adequate margin of safety, the operator of the system will connect the equalizing current connector to the bottom plate and then continue the electroslag remelting process. When the equalizing current connection has been made, the rate of melting of the electrodes 34 and 35 will again become balanced. Thus, the voltmeters 99 provide an important indication in bifilar electroslag remelting, particularly when the equalizing current connection is not initially used.

. 19 In the preferred embodiment of the invention, the electrodes either are in the form of slabs, in which case they are positioned in the mold as illustrated in FIG. 11

or 13, or the electrodes are square in cross section, in which case they are positioned in the mold as shown in FIG. 12 or 14. With both types of electrodes, the-mold is rectangular. To make ingots of different sizes only one horizontal dimension of the rectangular mold is changed. Thus, the molds shown in FIGS. 13 and 14, by being shorter only in one horizontal dimension of the mold, make smaller ingots than the molds in FIGS. 11 and 12. When slab-shaped electrodes are used to make different sized ingots, as shown in FIGS. 11 and 13, the thickness and the spacing of the slabs remain the same and the width of the slab is varied. Thus, to make the smaller ingot with the mold in FIG. 13, the width of the slab of. electrodes is decreased. It will be noted that the dimension of the mold, which is decreased in FIG. 13, extends in the same direction as the width dimension of the electrodes.

- When square electrodes are used to make ingots of different sizes, the electrodes of the same size are, used but the distance between the electrodes is changed. Thus, to make the smaller ingot. with the mold shown in FIG. 14, the distance between the electrodes is decreased. It will be noted that the dimension of the mold which is decreased to make the smaller ingot extends in the same direction as the dimension between the electrodes, which is reduced to make the smaller ingot. By using the above described techniques to make ingots of different sizes, the cost of the electrodes is significantly reduced because electrodes may be more readily made in large numbers if they are uniform in size.

When current first starts to flow through the electrodes and through the molten slag bath, the resulting current surge will set up an electromagnetic field tending to cause the electrodes to fly apart. This could cause the electrodes to come in contact with .the sidewalls of the mold. To prevent this from occurring, a support 101 is positioned on top of the mold and rollers 103 are mounted on this support. Two rollers are mounted along each long dimension of the rectangular angular mold will engage the square electrodes to prevent the square electrodes from flying apart as is shown in FIG. 12.

The above described system and method of electroslag remelting will produce high quality ingots. The bifilar technique described greatly reduces the amount of power required to produce a given size ingot. Many modifications may be made to the above described specific embodiments of the invention without departing from the spirit and scope of the invention, which is defined in the appended claims.

What is claimed is:

1. An electroslag remelting system comprising: a mold for forming an ingot under a bath of molten slag, said mold including electrically conducting sidewalls and a separable electrically conducting base plate, said sidewalls having an outwardly extending flange disllll posed on said base plate, and means for pressing said flange into electrical contact with said base plate to maintain a negligible resistance path therebetween; means for positioning either two electrodes or two groups of electrodes in said mold with the lower end portions thereof immersed in the molten slag bath within the mold; means for passingelectric current through said electrodes and providing current flow between each electrode or group of electrodes and the other electrode or group of electrodes, said current flow between said electrodes consisting of single phase current flow; and a conductor of equalizing current connected to said slag bath to provide a series circuit through said electrodes from said means for passing electric current in a manner to compensate for a difference of linear speeds of melting of the electrodes.

2. An electroslag remelting system as recited in claim ll, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said flange and said base plate. a

3. An electroslag remelting system comprising: a mold for forming an ingot under a bath of molten slag, said mold including electrically conducting sidewalls and a separable electrically conducting base plate, said sidewalls having an outwardly extending flange dis-' posed on said base plate, and means for pressing said flange into electrical contact with said base plate to maintain a negligible resistance path therebetween; means for positioning either two electrodes or two groups of electrodes in said mold with the lower end portions thereof immersed in the molten slag bath within said mold; and means for passing electric current through said electrodes and providing current flow between each electrode or group of electrodes and the other electrode or group of electrodes, said current flow between said electrodes consisting of single phase AC current flow; and means providing a circuit connection to the slag bath connected in series to said means for passing electric current.

4. An electroslag remelting system as recited in claim 3, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said flange and said base plate. i

5. An electroslag remelting system comprising: a mold for forming an ingot beneath a bath of molten slag, said mold including electrically conducting sidewalls and a separable electrically conducting base plate, and electrically conducting metal foil folded in a plurality of layers between said sidewalls and said base plate to assure a negligible resistance electrical connection therebetween; means for positioning at least one electrode in said mold with the lower end portion thereof immersed in said molten slag bath; and means for passing electric current through said electrode and said molten slag bath.

6. An electroslag remelting system comprising: a mold for fonning an ingot beneath a bath of molten slag, said mold including electrically conducting sidewalls and a separable electrically conducting base plate, and electrically conducting metal foil folded in a plurality of layers pressed between said sidewalls and said base plate to assure a negligible resistance electrical connection therebetween; means for positioning at least two electrodes in said mold with the lower end portions thereof immersed in said molten slag bath, and means for applying AC power between said electrodes to cause current to flow between said electrodes and through said molten slag bath.

7. An electroslag remelting system comprising a mold for forming an ingot under a bath of molten slag, said mold defining a recess in the inner wall thereof at the bottom of said mold, means for pressing a piece of metal against the side of said recess to provide electrical contact between said metal piece and said mold, means for positioning at least one electrode in said mold immersed in said bath of molten slag, and means for passing current through said electrode and said bath of molten slag.

8. An electroslag remelting system comprising a mold for forming an ingot under a bath of molten slag, said mold'defining a recess in the inner wall thereof at the bottom of said mold, means for pressing a piece of metal against the side of said recess to provide electrical contact between said metal piece and said mold, means for positioning at least two electrodes in said mold immersed in said bath of molten slag, and means for applying AC power between said electrodes to cause current to pass between said electrodes through said bath of molten slag.

9., A method of electroslag remelting comprising: joining an electroslag remelting mold with a bottom plate, said bottom plate having a recess in the upper wall thereof and having a contact means for pressing a piece of metal against the side of the recess to provide electrical contact between the metal piece and the bottom plate; placing a piece of metal in the recess; activating the contact means to press the piece of metal against the side of the recess; adding a bath of molten slag to the mold and covering the piece of metal therewith; immersing the lower end portion of at least one consumable electrode in the bath of molten slag; passing current through the electrode and the molten slag bath to cause the electrode to melt and an ingot to form in the'mold welded to the piece of metal; releasing the contact means; removing the formed ingot and the integrally welded piece of metal from the bottom plate.

10. A method as recited in claim 9 wherein said piece of metal is of the same composition as the ingot which is formed in said mold.

Eli. A method as defined by claim 9 wherein said step of passing current is carried out utilizing single phase alternating current.

12. An electroslag remelting system comprising a mold for forming an ingot under a bath of molten slag, means for positioning at least two electrodes in said mold immersed in the molten slag bath within said mold, means for applying AC power between said electrodes to cause electric current to pass between said electrodes through said molten slag bath, and means mounted on the upper portion of said mold adapted to act upon said electrodes, said means preventing said electrodes from moving apart in the opposite directions under the action of electromagnetic forces created between said electrodes upon application of power, when the current is caused to flow between said electrodes and through said molten slag bath.

113. An electroslag remelting system as recited in claim 12 wherein said means acting upon said electrodes, to prevent said'electrodes from moving apart comprises rollers supported by said mold.

14. An electroslag remelting system as defined in claim 12, said mold defining a recess in the inner wall thereof at the bottom of said mold and means for pressing a piece of metal against the side of said recess to provide electrical contact between said metal piece and said mold. 1

15. An electroslag remelting system as defined in claim 14, including a piece of metal in said recess and wherein said means for applying AC power between said electrodes includes a circuit connection to said mold bottom and thereby to said piece of metal.

16. An electroslag remelting system as defined in claim 12, said mold defining means in the inner wall thereof at the bottom of said mold for securing a piece of metal in the bottom of said mold with a portion of said piece of metal projecting above the said bottom to provide an electrical current path from said electrodes through the molten slag to said bottom of the mold.

17. An electroslag remelting system comprising: a mold for forming an ingot under a bath of molten slag, said mold defining a recess in the inner wall thereof at the bottom of said mold, a piece of metal in said recess with a portion of said metal projecting above the bottom of said mold; means for establishing electrical contact of said piece of metal against the side of said recess, means for positioning at least one electrode in said mold immersed in said bath of molten slag, and means for passing current through said electrode and said bath of molten slag.

18. An electroslag remelting system as defined in claim 17, including at least two electrodes and said means for passing current through said electrodes is means for applying AC power between said electrodes to cause current to pass between said electrodes through said bath of molten slag.

19. An electroslag remelting system as defined in claim 7, wherein said mold comprises sidewalls and a separable thick bottom wall.

20. An electroslag remelting system as defined in claim 7, wherein said mold is placed on a separable bottom plate and said recess is formed in said bottom plate.

21. An electroslag remelting system as defined in claim 7, wherein a piece of metal is positioned at least partly within said recess and is of the same composition as the ingot formed in said mold.

22. An electroslag remelting system as defined in claim 7 including a piece of metal in said recess and wherein said piece of metal projects from said recess up above the upper surface of the bottom of said mold.

23. An electroslag remelting system as defined in claim 7, wherein said recess is of rectangular shape.

24. An electroslag remelting system as defined in claim 7, wherein said means for pressing comprises a spring biased contact member.

25. An electroslag remelting system as defined in claim 8, wherein a piece of metal is positioned at least partly within said recess and is of the same composition as the ingot formed in said mold.

26. An electroslag remelting system as defined in claim 8, including a piece of metal in said recess and wherein said piece of metal projects from said recess up above the upper surface of the bottom of said mold.

27. An electroslag remelting system as defined in claim 7, wherein said mold includes electrically conducting sidewalls and a separable electrically conducting base plate, said sidwalls having an outwardly extending flange disposed on said base plate, and means for pressing said flange into electrical contact with said base plate to maintain a negligible resistance path therebetween.

28. An electroslag remelting system as defined in claim 27 wherein said base plate contains a plurality of straight parallel channels, means for passing a coolant through said channels to cool said base plate, said base plate comprising a bottom plate and a second plate beneath said bottom plate having a top surface contiguous with the bottom surface of said bottom plate, said plurality of channels being defined as recesses in the top surface of said second plate with the top surface of said channels being defined by the bottom surface of said bottom plate.

29. An electroslag remelting system as defined in claim 27 including means for providing relative motion between said electrodeand said mold selectively in two horizontal directions disposed perpendicularly with respect to one another for accomplishing symmetrical electrode positioning with respect to said mold as said electrodeis melted in said mold.

30. An electroslag remelting system as defined in claim 27 wherein at least two electrodes are positioned in said mold with the lower end portions thereof immersed in said bath of molten slag, and wherein said means for passing current through said electrodes and said bath of molten slag supplies AC power; and means mounted on the upper portion of said mold adapted to act upon said electrodes, said means preventing said electrodes from moving apart in opposite directions under the action of electromagnetic forces created between said electrodes upon application of power, when the current is caused to flow between said electrodes and through said molten slag bath.

31. An electroslag remelting system as defined in claim 27, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said flange and said base plate.

32. An electroslag remelting system as defined in claim 27, wherein either two electrodes or two groups of electrodes are positioned in said mold with the lower end portions thereof immersed in the molten slag bath within the mold, said means for passing current providing current flow between each electrode or group of electrodes and the other electrode or group of electrodes, said current flow between said electrodes consisting of single phase current flow.

33. An electroslag remelting system as defined in claim 32, wherein a conductor of equalizing current is connected to said slag bath to provide a series circuit through said electrodes from said means for passing current in a manner to compensate for a difference of linear speeds of melting of the electrodes.

34. An electroslag remelting system as defined by claim 27 wherein said means for passing current supplies AC power.

35. An electroslag remelting system, as defined in claim 7, wherein said mold includes sidewalls and a separable electrically conducting base plate, said base plate containing a plurality of straight parallel channels defined therethrough, means for passing a coolant through said channels to cool said base plate, said base plate comprising a bottom plate and a second plate beneath said bottom plate having a top surface contiguous with the bottom surface of said bottom plate, said plurality of channels being defined as recesses in the top surface of said second plate with the top surfaces of the channels being defined by the bottom surface of said bottom plate.

36. An electroslag remelting system as defined in claim 35, wherein at least two electrodes are positioned in said mold, means for applying AC power between said electrodes to cause electric current to pass between said electrodes through said molten slag bath, and means mounted on the upper portion of said mold adapted to act upon said electrodes,.said means preventing said electrodes from moving apart in opposite directions under the action of electromagnetic forces created between said electrodes upon application of power, when the current is caused to flow between said electrodes and through said molten slag bath.

37. An electroslag remelting system as defined in claim 35, including means for providing relative motion between said electrode and said mold selectively in two horizontal directions disposed perpendicularly with respect to one another for accomplishing symmetrical positioning with respect to said mold as said electrode is fed vertically into said mold.

38. An electroslag remelting system as defined in claim 35, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said mold sidewalls and said base plate.

39. An electroslag remelting system as defined in claim 35, wherein either two electrodes or two groups of electrodes are positioned in said mold with the lower end portions thereof immersed in themolten slag bath within the mold, said means for passing current providing current flow between each electrode or group of electrodes and the'other electrode or group of electrodes, said current flow between said electrodes consisting of single phase current flow.

40. An electroslag remelting system as defined in claim 39, wherein a conductor of equalizing current is connected to said slag bath to provide a series circuit through said electrodes from said means for passing current in a manner to compensate for a difference of linear speeds of melting of the electrodes.

41. An electroslag remelting system as defined in claim 1, wherein said base plate contains a plurality of straight parallel channels, means are provided for passing a coolant through said channels to cool said base plate, and said base plate comprises a bottom plate and a second plate beneath said bottom plate having a top surface contiguous with the bottom surface of said bottom plate, said plurality of channels being defined as recesses in the top surface of said second plate with the top surface of said channels being defined by the bottom surface of said bottom plate.

42. An electroslag remelting system as defined in claim 41, including means for providing relative motion between said electrodes and said mold selectively in two horizontal directions disclosed perpendicularly with respect to one another for accomplishing symmetrical electrode positioning with respect to said mold as said electrodes are melted in said mold.

43. An electroslag remelting system as defined in claim 41, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said flange and said base plate.

44. An electroslag remelting system as defined in claim 1, further including means mounted on the upper portion of said mold adapted to act upon said electrodes, said means preventing said electrodes from moving apart in opposite directions under the action of electromagnetic forces created between said electrodes upon application of power, when the current is caused to flow between said electrodes and through said molten slag bath.

45. An electroslag remelting system as defined by claim 44, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said flange and said base plate.

46. An electroslag remelting system as defined in claim 1, including means for providing relative motion between said electrodes and said mold selectively in two horizontal directions disposed perpendicularly with respect to one another for accomplishing symmet-.

rical electrode positioning with respect to said mold as said electrodes are melted in said mold.

47. An electroslag remelting system as defined i claim 46, wherein said base plate contains a pluralty of straight parallel channels, means for passing a coolant through said channels to cool said base plate, said base plate comprising a bottom plate and a second plate beneath said bottom plate having a top surface contiguous with the bottom surface of said bottom plate, said plurality of channels being defined as recesses in the top surface of said second plate with the top surface of said channels being defined by the bottom surface of said bottom plate.

48. An electroslag remelting system as defined in claim 46, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said flange and said base plate.

49. An electroslag remelting system as defined in 1 claim 7, including means for providing relative motion electrode is melted in said mold. 

1. An electroslag remelting system comprising: a mold for forming an ingot under a bath of molten slag, said mold including electrically conducting sidewalls and a separable electrically conducting base plate, said sidewalls having an outwardly extending flange disposed on said base plate, and means for pressing said flange into electrical contact with said base plate to maintain a negligible resistance path therebetween; means for positioning either two electrodes or two groups of electrodes in said mold with the lower end portions thereof immersed in the molten slag bath within the mold; means for passing electric current through said electrodes and providing current flow between each electrode or group of electrodes and the other electrode or group of electrodes, said current flow between said electrodes consisting of single phase current flow; and a conductor of equalizing current connected to said slag bath to provide a series circuit through said electrodes from said means for passing electric current in a manner to compensate for a difference of linear speeds of melting of the electrodes.
 2. An electroslag remelting system as recited in claim 1, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said flange and said base plate.
 3. An electroslag remelting system comprising: a mold for forming an ingot under a bath of molten slag, said mold including electrically conducting sidewalls and a separable electrically conducting base plate, said sidewalls having an outwardly extending flange disposed on said base plate, and means for pressing said flange into electrical contact with said base plate to maintain a negligible resistance path therebetween; means for positioning either two electrodes or two groups of electrodes in said mold with the lower end portions thereof immersed in the molten slag bath within said mold; and means for passing electric current through said electrodes and providing current flow between each electrode or group of electrodes and the other electrode or group of electrodes, said current flow between said electrodes consisting of single phase AC current flow; and means providing a circuit connection to the slag bath connected in series to said means for passing electric current.
 4. An electroslag remelting system as recited in claim 3, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said flange and said base plate.
 5. An electroslag remelting system comprising: a mold for forming an ingot beneath a bath of molten slag, said mold including electrically conducting sidewalls and a separable electrically conducting base plate, and electrically conducting metal foil folded in a plurality of layers between said sidewalls and said base plate to assure a negligible resistance electrical connection therebetween; means for positioning at least one electrode in said mold with the lower end portion thereof immersed in said molten slag bath; and means for passing electric current through said electrode and said molten slag batH.
 6. An electroslag remelting system comprising: a mold for forming an ingot beneath a bath of molten slag, said mold including electrically conducting sidewalls and a separable electrically conducting base plate, and electrically conducting metal foil folded in a plurality of layers pressed between said sidewalls and said base plate to assure a negligible resistance electrical connection therebetween; means for positioning at least two electrodes in said mold with the lower end portions thereof immersed in said molten slag bath, and means for applying AC power between said electrodes to cause current to flow between said electrodes and through said molten slag bath.
 7. An electroslag remelting system comprising a mold for forming an ingot under a bath of molten slag, said mold defining a recess in the inner wall thereof at the bottom of said mold, means for pressing a piece of metal against the side of said recess to provide electrical contact between said metal piece and said mold, means for positioning at least one electrode in said mold immersed in said bath of molten slag, and means for passing current through said electrode and said bath of molten slag.
 8. An electroslag remelting system comprising a mold for forming an ingot under a bath of molten slag, said mold defining a recess in the inner wall thereof at the bottom of said mold, means for pressing a piece of metal against the side of said recess to provide electrical contact between said metal piece and said mold, means for positioning at least two electrodes in said mold immersed in said bath of molten slag, and means for applying AC power between said electrodes to cause current to pass between said electrodes through said bath of molten slag.
 9. A method of electroslag remelting comprising: joining an electroslag remelting mold with a bottom plate, said bottom plate having a recess in the upper wall thereof and having a contact means for pressing a piece of metal against the side of the recess to provide electrical contact between the metal piece and the bottom plate; placing a piece of metal in the recess; activating the contact means to press the piece of metal against the side of the recess; adding a bath of molten slag to the mold and covering the piece of metal therewith; immersing the lower end portion of at least one consumable electrode in the bath of molten slag; passing current through the electrode and the molten slag bath to cause the electrode to melt and an ingot to form in the mold welded to the piece of metal; releasing the contact means; removing the formed ingot and the integrally welded piece of metal from the bottom plate.
 10. A method as recited in claim 9 wherein said piece of metal is of the same composition as the ingot which is formed in said mold.
 11. A method as defined by claim 9 wherein said step of passing current is carried out utilizing single phase alternating current.
 12. An electroslag remelting system comprising a mold for forming an ingot under a bath of molten slag, means for positioning at least two electrodes in said mold immersed in the molten slag bath within said mold, means for applying AC power between said electrodes to cause electric current to pass between said electrodes through said molten slag bath, and means mounted on the upper portion of said mold adapted to act upon said electrodes, said means preventing said electrodes from moving apart in the opposite directions under the action of electromagnetic forces created between said electrodes upon application of power, when the current is caused to flow between said electrodes and through said molten slag bath.
 13. An electroslag remelting system as recited in claim 12 wherein said means acting upon said electrodes to prevent said electrodes from moving apart comprises rollers supported by said mold.
 14. An electroslag remelting system as defined in claim 12, said mold defining a recess in the inner wall thereof at the bottom of said mold and means for pressing a Piece of metal against the side of said recess to provide electrical contact between said metal piece and said mold.
 15. An electroslag remelting system as defined in claim 14, including a piece of metal in said recess and wherein said means for applying AC power between said electrodes includes a circuit connection to said mold bottom and thereby to said piece of metal.
 16. An electroslag remelting system as defined in claim 12, said mold defining means in the inner wall thereof at the bottom of said mold for securing a piece of metal in the bottom of said mold with a portion of said piece of metal projecting above the said bottom to provide an electrical current path from said electrodes through the molten slag to said bottom of the mold.
 17. An electroslag remelting system comprising: a mold for forming an ingot under a bath of molten slag, said mold defining a recess in the inner wall thereof at the bottom of said mold, a piece of metal in said recess with a portion of said metal projecting above the bottom of said mold; means for establishing electrical contact of said piece of metal against the side of said recess, means for positioning at least one electrode in said mold immersed in said bath of molten slag, and means for passing current through said electrode and said bath of molten slag.
 18. An electroslag remelting system as defined in claim 17, including at least two electrodes and said means for passing current through said electrodes is means for applying AC power between said electrodes to cause current to pass between said electrodes through said bath of molten slag.
 19. An electroslag remelting system as defined in claim 7, wherein said mold comprises sidewalls and a separable thick bottom wall.
 20. An electroslag remelting system as defined in claim 7, wherein said mold is placed on a separable bottom plate and said recess is formed in said bottom plate.
 21. An electroslag remelting system as defined in claim 7, wherein a piece of metal is positioned at least partly within said recess and is of the same composition as the ingot formed in said mold.
 22. An electroslag remelting system as defined in claim 7 including a piece of metal in said recess and wherein said piece of metal projects from said recess up above the upper surface of the bottom of said mold.
 23. An electroslag remelting system as defined in claim 7, wherein said recess is of rectangular shape.
 24. An electroslag remelting system as defined in claim 7, wherein said means for pressing comprises a spring biased contact member.
 25. An electroslag remelting system as defined in claim 8, wherein a piece of metal is positioned at least partly within said recess and is of the same composition as the ingot formed in said mold.
 26. An electroslag remelting system as defined in claim 8, including a piece of metal in said recess and wherein said piece of metal projects from said recess up above the upper surface of the bottom of said mold.
 27. An electroslag remelting system as defined in claim 7, wherein said mold includes electrically conducting sidewalls and a separable electrically conducting base plate, said sidewalls having an outwardly extending flange disposed on said base plate, and means for pressing said flange into electrical contact with said base plate to maintain a negligible resistance path therebetween.
 28. An electroslag remelting system as defined in claim 27 wherein said base plate contains a plurality of straight parallel channels, means for passing a coolant through said channels to cool said base plate, said base plate comprising a bottom plate and a second plate beneath said bottom plate having a top surface contiguous with the bottom surface of said bottom plate, said plurality of channels being defined as recesses in the top surface of said second plate with the top surface of said channels being defined by the bottom surface of said bottom plate.
 29. An electroslag remelting system as defined in claim 27 including means foR providing relative motion between said electrode and said mold selectively in two horizontal directions disposed perpendicularly with respect to one another for accomplishing symmetrical electrode positioning with respect to said mold as said electrode is melted in said mold.
 30. An electroslag remelting system as defined in claim 27 wherein at least two electrodes are positioned in said mold with the lower end portions thereof immersed in said bath of molten slag, and wherein said means for passing current through said electrodes and said bath of molten slag supplies AC power; and means mounted on the upper portion of said mold adapted to act upon said electrodes, said means preventing said electrodes from moving apart in opposite directions under the action of electromagnetic forces created between said electrodes upon application of power, when the current is caused to flow between said electrodes and through said molten slag bath.
 31. An electroslag remelting system as defined in claim 27, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said flange and said base plate.
 32. An electroslag remelting system as defined in claim 27, wherein either two electrodes or two groups of electrodes are positioned in said mold with the lower end portions thereof immersed in the molten slag bath within the mold, said means for passing current providing current flow between each electrode or group of electrodes and the other electrode or group of electrodes, said current flow between said electrodes consisting of single phase current flow.
 33. An electroslag remelting system as defined in claim 32, wherein a conductor of equalizing current is connected to said slag bath to provide a series circuit through said electrodes from said means for passing current in a manner to compensate for a difference of linear speeds of melting of the electrodes.
 34. An electroslag remelting system as defined by claim 27 wherein said means for passing current supplies AC power.
 35. An electroslag remelting system, as defined in claim 7, wherein said mold includes sidewalls and a separable electrically conducting base plate, said base plate containing a plurality of straight parallel channels defined therethrough, means for passing a coolant through said channels to cool said base plate, said base plate comprising a bottom plate and a second plate beneath said bottom plate having a top surface contiguous with the bottom surface of said bottom plate, said plurality of channels being defined as recesses in the top surface of said second plate with the top surfaces of the channels being defined by the bottom surface of said bottom plate.
 36. An electroslag remelting system as defined in claim 35, wherein at least two electrodes are positioned in said mold, means for applying AC power between said electrodes to cause electric current to pass between said electrodes through said molten slag bath, and means mounted on the upper portion of said mold adapted to act upon said electrodes, said means preventing said electrodes from moving apart in opposite directions under the action of electromagnetic forces created between said electrodes upon application of power, when the current is caused to flow between said electrodes and through said molten slag bath.
 37. An electroslag remelting system as defined in claim 35, including means for providing relative motion between said electrode and said mold selectively in two horizontal directions disposed perpendicularly with respect to one another for accomplishing symmetrical positioning with respect to said mold as said electrode is fed vertically into said mold.
 38. An electroslag remelting system as defined in claim 35, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said mold sidewalls and said base plate.
 39. An electroslag remelting system as defined in claim 35, wherein either two electrodes or two groups of electrodes are positioned in said molD with the lower end portions thereof immersed in the molten slag bath within the mold, said means for passing current providing current flow between each electrode or group of electrodes and the other electrode or group of electrodes, said current flow between said electrodes consisting of single phase current flow.
 40. An electroslag remelting system as defined in claim 39, wherein a conductor of equalizing current is connected to said slag bath to provide a series circuit through said electrodes from said means for passing current in a manner to compensate for a difference of linear speeds of melting of the electrodes.
 41. An electroslag remelting system as defined in claim 1, wherein said base plate contains a plurality of straight parallel channels, means are provided for passing a coolant through said channels to cool said base plate, and said base plate comprises a bottom plate and a second plate beneath said bottom plate having a top surface contiguous with the bottom surface of said bottom plate, said plurality of channels being defined as recesses in the top surface of said second plate with the top surface of said channels being defined by the bottom surface of said bottom plate.
 42. An electroslag remelting system as defined in claim 41, including means for providing relative motion between said electrodes and said mold selectively in two horizontal directions disclosed perpendicularly with respect to one another for accomplishing symmetrical electrode positioning with respect to said mold as said electrodes are melted in said mold.
 43. An electroslag remelting system as defined in claim 41, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said flange and said base plate.
 44. An electroslag remelting system as defined in claim 1, further including means mounted on the upper portion of said mold adapted to act upon said electrodes, said means preventing said electrodes from moving apart in opposite directions under the action of electromagnetic forces created between said electrodes upon application of power, when the current is caused to flow between said electrodes and through said molten slag bath.
 45. An electroslag remelting system as defined by claim 44, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said flange and said base plate.
 46. An electroslag remelting system as defined in claim 1, including means for providing relative motion between said electrodes and said mold selectively in two horizontal directions disposed perpendicularly with respect to one another for accomplishing symmetrical electrode positioning with respect to said mold as said electrodes are melted in said mold.
 47. An electroslag remelting system as defined in claim 46, wherein said base plate contains a pluralty of straight parallel channels, means for passing a coolant through said channels to cool said base plate, said base plate comprising a bottom plate and a second plate beneath said bottom plate having a top surface contiguous with the bottom surface of said bottom plate, said plurality of channels being defined as recesses in the top surface of said second plate with the top surface of said channels being defined by the bottom surface of said bottom plate.
 48. An electroslag remelting system as defined in claim 46, wherein electrically conducting metal foil folded in a plurality of layers is pressed between said flange and said base plate.
 49. An electroslag remelting system as defined in claim 7, including means for providing relative motion between said electrode and said mold selectively in two horizontal directions disposed perpendicularly with respect to one another for accomplishing symmetrical electrode positioning with respect to said mold as said electrode is melted in said mold. 